From cea6c387a3c29fa68dfbd37fff1aba082354442b Mon Sep 17 00:00:00 2001
From: Sainnhe Park <i@sainnhe.dev>
Date: Fri, 3 Feb 2023 16:42:37 +0800
Subject: [PATCH] s0046

---
 include/s0046_permutations.hpp | 13 +++++++++++++
 notes/src/SUMMARY.md           |  1 +
 notes/src/permute.md           |  3 +++
 src/s0046_permutations.cpp     | 31 +++++++++++++++++++++++++++++++
 4 files changed, 48 insertions(+)
 create mode 100644 include/s0046_permutations.hpp
 create mode 100644 notes/src/permute.md
 create mode 100644 src/s0046_permutations.cpp

diff --git a/include/s0046_permutations.hpp b/include/s0046_permutations.hpp
new file mode 100644
index 0000000..40122aa
--- /dev/null
+++ b/include/s0046_permutations.hpp
@@ -0,0 +1,13 @@
+#ifndef S0046_PERMUTATIONS_HPP
+#define S0046_PERMUTATIONS_HPP
+
+#include <vector>
+
+using namespace std;
+
+class S0046 {
+ public:
+  vector<vector<int>> permute(vector<int>& nums);
+};
+
+#endif
diff --git a/notes/src/SUMMARY.md b/notes/src/SUMMARY.md
index 600c238..3fb8699 100644
--- a/notes/src/SUMMARY.md
+++ b/notes/src/SUMMARY.md
@@ -44,6 +44,7 @@
 - [组合问题](./combinations.md)
 - [切割问题](./split.md)
 - [子集问题](./subsets.md)
+- [排列问题](./permute.md)
 
 # STL
 
diff --git a/notes/src/permute.md b/notes/src/permute.md
new file mode 100644
index 0000000..7ac49ba
--- /dev/null
+++ b/notes/src/permute.md
@@ -0,0 +1,3 @@
+# 排列问题
+
+## [46. 全排列](https://leetcode.cn/problems/permutations/)
diff --git a/src/s0046_permutations.cpp b/src/s0046_permutations.cpp
new file mode 100644
index 0000000..24163fd
--- /dev/null
+++ b/src/s0046_permutations.cpp
@@ -0,0 +1,31 @@
+#include "s0046_permutations.hpp"
+
+void permuteDFS(vector<int> &path, vector<vector<int>> &result,
+                vector<bool> &used, vector<int> &nums) {
+  int len = nums.size();
+  // 终止条件
+  if (path.size() == len) {
+    result.push_back(path);
+    return;
+  }
+
+  // 开始迭代
+  for (int i{0}; i < len; ++i) {
+    // 如果当前元素使用过，则跳过
+    if (used[i]) continue;
+    // 否则处理当前节点
+    path.push_back(nums[i]);
+    used[i] = true;
+    permuteDFS(path, result, used, nums);
+    used[i] = false;
+    path.pop_back();
+  }
+}
+
+vector<vector<int>> S0046::permute(vector<int> &nums) {
+  vector<int> path{};
+  vector<vector<int>> result{};
+  vector<bool> used(nums.size(), false);
+  permuteDFS(path, result, used, nums);
+  return result;
+}